The present invention relates to solid-state imaging devices and methods of manufacturing the solid-state imaging devices.
In reducing cell sizes to 1 μm or smaller in conventional metal oxide semiconductor (MOS) image sensors, reduction in the thicknesses of photo diodes for preventing mixed colors (crosstalk) degrades light absorption efficiency and reduces the number of saturated electrons. To address the problems, Japanese Unexamined Patent Publication No. 2011-054746 suggests a multilayer image sensor, in which a photoelectric conversion film is stacked on a semiconductor (e.g., crystal silicon) substrate including a pixel circuit with an insulating film interposed between the substrate and the conversion film.
In multilayer image sensors, photoelectric conversion films are made of a material with a higher light absorption coefficient such as an amorphous silicon or an organic film. Since no photo diode is buried in a semiconductor substrate, mixed colors can be reduced. In addition, the capacity of photoelectric converters increases, thereby increasing the number of saturated electrons.